Why GitLab isn't as Popular as GitHub for Open-Source
GitLab is open-source, GitHub is closed source. So why does GitHub attract more open-source projects? Obviously, the network effect of GitHub is one reason but I think there's another: On GitHub I can contribute to multiple organizations with a single identity, on GitLab I need separate identities to contribute to multiple organizations.
On a day-to-day basis, the impact is that GitLab is more convenient than GitHub. Contributors that belong to multiple organizations do not need to log out and back in on GitHub as they do on GitLab. There's just one "to-do list" for everything, rather than for each individual account.
However, there's also a more human reason: Having a single identity makes coding social. On GitHub, you get all the "credit" for your contribution. It's rewarding to see the contribution graph get darker and darker green on GitHub, but on GitLab those contributions can get split across accounts.
If GitLab wants to get serious about attracting open-source to its platform, they need to allow their users to have a single identity on that platform.
Deeper Knowledge on GitLab
Tips for working in GitLab CI/CD
Broader Topics Related to GitLab
A distributed version-control system to track changes, typically for software development projects